Cryostat arrangements and mounting arrangements for cryostats
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cryostat arrangements face challenges in conveniently installing and removing cryocoolers while maintaining good thermal contact and minimizing thermal conduction paths, especially at cold temperatures, which is essential for superconducting magnet applications like MRI systems.
Innovation Solution
A cryocooler mounting arrangement featuring a clamping ring made of PTFE that contracts at ambient operating temperatures to provide clamping action, with heating means for expansion to aid in engagement and disengagement, and a compact design with retaining shoulder portions on fingers to maintain thermal contact and minimize heat leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamping mechanism is used to maintain thermal contact between the coldhead and cryostat interior, then thermal contact is improved, but the complexity of the mounting arrangement increases
Solution Approach 1:
The clamping ring is made of PTFE material that undergoes thermal contraction when cooled to operating temperature, providing automatic clamping force to maintain thermal contact between the coldhead and cryostat interior without requiring additional actuation mechanisms
Solution Approach 2:
The PTFE clamping ring serves dual functions: it provides thermal conduction path and simultaneously generates clamping force through thermal contraction, eliminating the need for separate mechanical fastening mechanisms
2Ease of operation
If the cryocooler can be easily installed and removed, then ease of operation is improved, but thermal contact may be compromised
Solution Approach 1:
The PTFE clamping ring is heated during installation to expand and become more compliant, allowing easy engagement with the coldhead and cryostat interior, then automatically contracts when cooled to operating temperature to provide secure thermal contact
Solution Approach 2:
The physical state of the PTFE clamping ring is changed between expanded (during installation) and contracted (during operation) states, enabling both easy manipulation and reliable thermal contact at different operational phases
3Loss of energy
If thermal conduction paths are minimized, then heat leakage is reduced, but thermal contact between coldhead and cryostat interior may be insufficient
Solution Approach 1:
The mounting arrangement provides localized thermal conduction at the coldhead interface through the PTFE clamping ring, while the rest of the cryostat structure maintains thermal insulation, achieving efficient heat transfer only where needed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables easy interchange of cryocoolers during initial cooldown and ongoing operation, facilitates maintenance, and maintains robust thermal contact, reducing thermal conduction paths and heat leakage, while allowing for a compact and efficient design.
Implementation Method 1
The clamping ring may be arranged to contract in response to the ambient operating temperature in the cryostat to provide the clamping action
Implementation Method 2
The clamping ring may be of PTFE (Polytetrafluoroethylene)... Heating means may be provided for heating the clamping ring to cause expansion thereof for aiding in the release and/or location of the finger portions on the bearing surface
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A cryocooler mounting arrangement and magnets and cryostats including such an arrangement. The arrangement is for mounting the coldhead 21 of a cryocooler 2 in a cryostat 1 for allowing the extraction of heat from the interior of the cryostat by the cryocooler. The mounting arrangement comprises a coldhead interface portion 22a, 22b for mounting on the coldhead 21 and a sock portion 3 for mounting in the cryostat 1 and arranged for receiving the coldhead 21. The sock portion 3 comprises a receiving interface portion 32a, 32b for receiving the coldhead interface portion so as to provide thermal contact therebetween and hence to provide thermal contact between the coldhead and the interior of the cryostat. The coldhead interface portion comprises plurality of flexible finger portions 23a, 23b and the receiving interface portion comprises a bearing surface 322a, 322b against which the finger portions are arranged to rest. The mounting arrangement further comprises a clamping ring 4a, 4b for releasably clamping the finger portions 23a, 23b against the bearing surface 322a, 322b to ensure thermal contact between the coldhead interface and the receiving interface. The clamping ring 4a, 4b is held in a recess on the fingers. An outer interface portion 5 is provided at the outer vacuum wall of the cryostat 1.